How will enlargement of the European Union (EU) affect prospects for the euro as an international currency? Will the eventual addition of ten or more new members to the Economic and Monetary Union (EMU) enhance the euro’s ability to challenge the US dollar for global monetary supremacy? Previously, I have argued that Europe’s joint currency is fated to remain a distant second to America’s greenback long into the foreseeable future (Cohen 2003). In this chapter I extend my earlier analysis to consider the impact of enlargement on the euro’s international role. My conclusion now is, if anything, even more skeptical than before. Enlargement, I submit, will diminish, not expand, the euro’s attractiveness as a rival to the greenback.